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Electrophysiological responses to vagus nerve stimulation in rats

Lies Mollet (UGent), Robrecht Raedt (UGent), Jean Delbeke (UGent), RIEM EL TAHRY (UGent), Veerle De Herdt (UGent), Alfred Meurs (UGent), Wytse Wadman (UGent), Kristl Vonck (UGent) and Paul Boon (UGent)
(2012) EPILEPSIA. 53(suppl. 5). p.170-170
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Abstract
Introduction: Vagus nerve stimulation (VNS) for refractory epilepsy requires optimization of stimulation parameters in order to improve clinical outcome. Experimental research showed that VNS exerts its effect by activating afferent, fast-conducting fibers. There is however a clear need for an objective parameter reflecting effective stimulation. We recorded electrophysiological responses to stimulation of the vagus nerve in rats. Methods: Rats were implanted with a stimulation electrode around the left cervical vagus nerve. Recordings were made using thin point electrodes placed on the vagus nerve rostral to the stimulating cathode. The vagus nerve was stimulated under anesthesia with a charge-balanced biphasic pulse (5µs/phase). Results: The electrophysiological response recorded from the vagus nerve consisted of an early and a late component, identified as respectively an afferent compound action potential (CAP) and a far field potential of the larynx motor evoked potential (LMEP). The I50% for the CAP and LMEP (respectively 1.9 ± 0.3 mA and 1.6 ± 0.1 mA) were not significantly different. Mean latency for the CAP and LMEP at 1.3 ± 0.3 mm rostral to the stimulating cathode, were 0.4 ± 0.1 ms and 2.0 ± 0.2 ms respectively. At 3.1 ± 0.6 mm rostral to the stimulating cathode, a difference in response latency was measured for the CAP. Conduction velocity was calculated to be 32.5 ± 2.5 m/s. Based on the measured distance between the cuff electrode and the laryngeal muscles, conduction velocity of the efferent action potentials leading to the LMEP was calculated to be 33.3 ± 1.3 m/s. Mean rheobase and chronaxy for the CAP were respectively 35.0 ± 5.0 µA and 40.0 ± 3.5 µs. Conclusion: Short biphasic pulses with an intensity of 1.5-2.5mA activate fast-conducting vagus nerve fibers. Our set-up can be used to evaluate the effects of different stimulation parameters at the level of the cervical vagus nerve in epilepsy models.

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Chicago
Mollet, Lies, Robrecht Raedt, Jean Delbeke, RIEM EL TAHRY, Veerle De Herdt, Alfred Meurs, Wytse Wadman, Kristl Vonck, and Paul Boon. 2012. “Electrophysiological Responses to Vagus Nerve Stimulation in Rats.” In Epilepsia, 53:170–170.
APA
Mollet, L., Raedt, R., Delbeke, J., EL TAHRY, R., De Herdt, V., Meurs, A., Wadman, W., et al. (2012). Electrophysiological responses to vagus nerve stimulation in rats. EPILEPSIA (Vol. 53, pp. 170–170). Presented at the 10th European congress on Epileptology.
Vancouver
1.
Mollet L, Raedt R, Delbeke J, EL TAHRY R, De Herdt V, Meurs A, et al. Electrophysiological responses to vagus nerve stimulation in rats. EPILEPSIA. 2012. p. 170–170.
MLA
Mollet, Lies, Robrecht Raedt, Jean Delbeke, et al. “Electrophysiological Responses to Vagus Nerve Stimulation in Rats.” Epilepsia. Vol. 53. 2012. 170–170. Print.
@inproceedings{3051388,
  abstract     = {Introduction: Vagus nerve stimulation (VNS) for refractory epilepsy requires optimization of stimulation parameters in order to improve clinical outcome. Experimental research showed that VNS exerts its effect by activating afferent, fast-conducting fibers. There is however a clear need for an objective parameter reflecting effective stimulation. We recorded electrophysiological responses to stimulation of the vagus nerve in rats.
Methods: Rats were implanted with a stimulation electrode around the left cervical vagus nerve. Recordings were made using thin point electrodes placed on the vagus nerve rostral to the stimulating cathode. The vagus nerve was stimulated under anesthesia with a charge-balanced biphasic pulse (5{\textmu}s/phase).
Results: The electrophysiological response recorded from the vagus nerve consisted of an early and a late component, identified as respectively an afferent compound action potential (CAP) and a far field potential of the larynx motor evoked potential (LMEP). The I50\% for the CAP and LMEP (respectively 1.9 {\textpm} 0.3 mA and 1.6 {\textpm} 0.1 mA) were not significantly different. Mean latency for the CAP and LMEP at 1.3 {\textpm} 0.3 mm rostral to the stimulating cathode, were 0.4 {\textpm} 0.1 ms and 2.0 {\textpm} 0.2 ms respectively. At 3.1 {\textpm} 0.6 mm rostral to the stimulating cathode, a difference in response latency was measured for the CAP. Conduction velocity was calculated to be 32.5 {\textpm} 2.5 m/s. Based on the measured distance between the cuff electrode and the laryngeal muscles, conduction velocity of the efferent action potentials leading to the LMEP was calculated to be 33.3 {\textpm} 1.3 m/s. Mean rheobase and chronaxy for the CAP were respectively 35.0 {\textpm} 5.0 {\textmu}A and 40.0 {\textpm} 3.5 {\textmu}s.
Conclusion: Short biphasic pulses with an intensity of 1.5-2.5mA activate fast-conducting vagus nerve fibers. Our set-up can be used to evaluate the effects of different stimulation parameters at the level of the cervical vagus nerve in epilepsy models.},
  author       = {Mollet, Lies and Raedt, Robrecht and Delbeke, Jean and EL TAHRY, RIEM and De Herdt, Veerle and Meurs, Alfred and Wadman, Wytse and Vonck, Kristl and Boon, Paul},
  booktitle    = {EPILEPSIA},
  issn         = {0013-9580},
  language     = {eng},
  location     = {London, UK},
  number       = {suppl. 5},
  pages        = {170--170},
  title        = {Electrophysiological responses to vagus nerve stimulation in rats},
  volume       = {53},
  year         = {2012},
}

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